Parallel barrier supporting system having spring movement limiter

ABSTRACT

A three-point suspension system for parallax barriers wherein two of the supporting points inherently define a pivot plane and a retaining means is positioned adjacent the third supporting point for reducing the tendency of the barrier to pivot.

United States Patent [1 1 Kautz et al.

[451 July 3,1973

[ PARALLEL BARRIER SUPPORTING SYSTEM HAVING SPRING MOVEMENT LIMITER [75] Inventors: George R. Kautz, Seneca Falls; Alan T. Kuryla, Geneva, both of N.Y.

[73] Assignee: GTE Sylvania Incorporated, Seneca Falls, NY.

[22] Filed: Jan. 8, 1969 [21] Appl. No.: 789,691

[52] US. Cl 313/85 S, 313/286 [51] Int. Cl H01j 29/02, 1101 29/06 [58] Field of Search 313/85 S, 92 B [56] References Cited UNITED STATES PATENTS 3,524,972 8/1970 Cooper et a1 313/85 S 3,330,980 7/1967 Shrader 313/85 S 3,370,194 2/1968 Schwartz et al. 313/92 B 3,454,813 7/1969 Lewinson 313/85 S X Primary Examiner-Robert Segal Attorney-Norman J. OMalley, Cyril A. Krenzer and William H. McNeill [57] ABSTRACT A three-point suspension system for parallax barriers wherein two of the supporting points inherently define a pivot plane and a retaining means is positioned adjacent the third supporting point for reducing the tendency of the barrier to pivot.

6 Claims, 6 Drawing Figures Patented July 3, 1973 3 Sheets-Sheet 1 J a 1 s. r a u ,A L x Z .Ik N 7 7 7 INVENTORS GEORGE R. KRUTZ 2 ALAN T. KURYLA ATTORNEY Patented Jul 3, 1973 3,743,818

3 Sheets-Sheet 2 E INVENTORS GEORGE a. KAUTZ a. PR ART ALAN T. KURYLA ATTORNEY Patented July 3, 1973 I 3,743,818

3 Sheets-Sheet 5 INVENTORS GEORGE R. KAUTZ 8 ALAN T. KURYLA ATTORNEY PARALLEL BARRIER SUPPORTING SYSTEM HAVING SPRING MOVEMENT LIMITER BACKGROUND OF THE INVENTION This invention relates to color cathode ray tubes and more particularly to means for supporting the parallax barrier therein. Color cathode ray tubes of the type currently being utilized in color television receivers employ a patterned screen of different colored lightemitting phosphors. An electron beam source, which generally comprises an electron gun for each of the phosphors on the screen, is positioned remotely from the screen. A parallax barrier for aiding in color selection is positioned intermediate the screen and the electron source, but closer to the screen. Because of the manner of fabricating the screen (see U.S. Pat. No. 3,025,161 for a detailed analysis of one method), the parallax barrier must be releasably mounted in the tube. This is accomplished by means of a plurality of leaf support springs which are fastened either at one of their ends to a side wall of the barrier, or to an intermediate support which is attached to the side wall and at their free ends cooperate with holding means, for example, studs, which are formed on an interior side wall of the cathode ray tube. There are two currently prevalent systems of support being utilized, one of which employs four support springs and the other of which employs three. This invention relates specifically to the latter system.

A three-point support system has distinct advantages over other systems in that the three points inherently define a plane, thus making assembly and disassembly much easier. However, a certain disadvantage exists under some conditions with the three-point system. To understand this disadvantage, a knowledge of the geometry of the system is necessary.

In the current family of color television tubes, the display area of the screen is substantially rectangular with an aspect ratio of approximately 4 to 3. The long side of the rectangle is horizontally positioned for normal viewing. One of the support springs is positioned on one of the long sides, generally the uppermost, and the other two are positioned on the two short sides. The short side springs are substantially oppositely disposed from one another and are approximately 90 to 120 from the uppermost spring to equalize the support as much as possible. Because of the rectangular aspect ratio of the tubes, it is sometimes not possible to achieve perfect symmetry in the spring spacing; however, it is desirable to come as close to this as possible.

The problem arises because the substantially oppositely disposed side springs inherently define therebetween a pivot plane. If the tube, when mounted in a receiver, is subjected to a severe jolt, such as from being dropped, the upper portion of the barrier may be pitched forward,-pivoting about the plane defined by the two side springs. If the jolt is severe enough, the welds joining the top spring may be fractured, or the spring may be forced beyond its elastic limit resulting in permanent deformation thereto. If either of the above occur, the result is a loss of registration between the screen and the apertures in the barrier and the tube will no longer perform properly. The amount of shock necessary to cause the above-described malfunction is not excessive and may quite readily occur during normal shipping of the receivers. To test for the likelihood of this occurrence, most television receiver manufacturers subject their completed receivers to a drop test; in accordance with standard RETMA procedures. If a given number of tubes so tested fail the test, a whole shipment of tubes may be rejected and returned to the tube manufacturer for rebuilding, entailing a tremendous added expense.

OBJECTS AND SUMMARY OF THE INVENTION It is, therefore, an object of the invention to enhance the structure of color cathode ray tubes.

It is another object of the invention to obviate the disadvantages of the prior art.

It is yet another object of the invention to provide a more rugged color cathode ray tube.

These and other objects are accomplished in one aspect of the invention by the provision of a color cathode ray tube employing a three-point suspension system which has means associated with one of the support springs for restricting the tendency of the barrier to pivot about the plane defined by the other two support springs.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic sectional view of a greatly simplified color cathode ray tube.

FIG. 2 is a sectional plan view of the screen portion of a color cathode ray tube employing the invention;

FIG. 3 is a perspective view of a parallax barrier employing the invention;

FIG. 4 is a diagrammatic view of the amount of movement in a prior art tube when viewed along a line such as 4-4 of FIG. 2;

FIG. 5 is a view similar to FIG. 4 showing the amount of barrier movement in a tube utilizing the invention;

and

FIG. 6 is a partial elevational view of a barrier incorporating one embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS For a better understanding of the present invention together with other objects, advantages and capabilities thereof, reference is made to the following disclosure and appended claims in connection with the abovedescribed drawings.

Referring now to the invention with greater particularity, there is shown in FIG. 1 a color cathode ray tube 10 having a face plate 12 with a patterned phosphor screen 14 disposed on the interior surface thereof. A peripheral side wall 16 extends from the face plate 12 and joins a substantially funnel-shaped body l8. The narrow end of the funnel terminates in a cylindrical neck 20 which encloses an electron source 22 in the form of a plurality of electron guns. A parallax barrier 24 is releasably mounted within the tube adjacent the screen portion. The tube is evacuated as is conventional in the artand is provided with suitable leads (not shown) for making electrical connection to the proper components.

The parallax barrier 24 comprises a relatively fragile apertured portion 26 which is affixed at its peripheral edge to a relatively rigid frame 28. The frame provides the parallax barrier side walls 30 to which the springs are attached. The configuration of the apertures in portion 26 may be either substantially circular or rectangular depending upon the screen pattern.

Referring now to FIG. 2 the supporting system may be seen more clearly as comprising three support springs; an uppermost spring 32; and two short side springs 34a and 34b, respectively. In FIGS. 2, 3 and 6 the springs are shown as being attached to the side walls 30 of the barrier frame 28 through the intermediary of temperature-compensating bimetallic base plate 36, which may be of the type described in US. Pat. No. 3,330,980. In FIGS. 4 and the base plate 36 is eliminated for the purpose of clarity and the springs are shown as being attached directly to the side wall. The apparatus of the invention is equally applicable to either type of mounting system.

As can be seen in FIG. 2, the two side springs 34a and 34b are substantially oppositely disposed and define therebetween a pivot plane, designated herein as 38. This pivot plane is generally positioned substantially below the horizontal axis of the tube and obviously the greater the distance it is so removed from the horizontal axis the greater will be the tendency to pivot.

To restrict the tendency to pivot, means 40 is formed adjacent the uppermost spring 32. The pivot-restricting means 40 comprises an upright segment 42 which is fixed on side wall, 30 and extends in a direction normal thereto. It is positioned on the side of the spring remote from the screen. It may take several forms but in a preferred embodiment of the invention it forms one leg of an L-shaped member which has its other leg 43 welded or otherwise permanently affixed to side wall 30.

It should be noted here that the purpose of the invention is not necessarily to completely stop the pivoting action but to at least restrict the amount of movement of the barrier to that which is less than the amount necessary to fracture the welds or which is within the elastic limits of the spring so that permanent deformation will not result.

The movement that occurs may be seen in FIG. 4, which illustrates a prior art tube that does not incorporate the invention. Herein, the solid portion of the drawing illustrates the normal position of the barrier and the phantomed portion illustrates the movement that occurs when the tube is subjected to a severe jolt. The upper portion of the barrier pitches forward at such time, pivoting about the inherently defined pivot plane 38. The action that occurs is a twisting one since the uppermost spring 32 is fixed at one of its ends 44 to the side wall 30 and at its other end 46 is free to rotate about the stud 48 which is fixed in face plate side wall 16. This twisting action exerts considerable strain upon the welds fastening end 44 to side wall 30. When the strain applied is'sufficient, these welds may fracture and the barrier will not return to its normal position, thus rendering the tube inoperative. If the welds are strong enough to hold, and the strain is sufficient, then the elastic limit of the spring may be exceeded with the same result.

The movement of the barrier when the instant invention is utilized is shown in FIG. 5. Now, undera similar jolt the barrier begins to move forward until the spring 32 hits pivot restricting means 40; then, because the spring 32 is bound on stud 48 and cannot move, the frame binds on means 40 and its movement is stopped before any of the above-described deleterious effects can occur. After the duration of the shock or jolt, the natural resiliency of the spring will return the barrier to its original position.

Thus, it will be seen that incorporation of this invention into color cathode ray tubes obviates the disadvantages of the prior art. The structure of the tube is enhanced and ruggedized providing a much more durable tube.

While there have been shown and described what are at present considered the preferred embodiments of the invention, it will be obvious to those skilled in the art that various changes and modifications may be made therein without departing from the scope of the invention as defined by the appended claims.

We claim:

1. A substantially rectangular color cathode ray tube comprising: an evacuated envelope having at one end an enlarged face plate portion with a mosaic phosphor screen on the interior surface thereof and at the other end thereof an electron gun formed to provide electron beams directed to impinge upon said screen; and a parallax barrier to aid in color selection mounted adjacent said screen, said barrier comprising a relatively fragile foraminated portion attached at its peripheral edge to a circumferential frame, said barrier being supported by means of three elongated support springs attached at one of their ends to a side wall of said frame and at the other of their ends to a side wall of said tube, two of said springs being attached to the short sides of said frame and the third spring being attached to one of the long sides; and extending therealong substantially parallel to the direction of said long side; said two of said springs being oppositely positioned to inherently define a pivot plane therebetween; and means formed adjacent said third spring and having a flat side substantially parallel thereto and attached to said frame and extending therefrom in a direction substantially normal to said frame for restricting the tendency of said barrier to pivot when said tube is dropped upon the edge opposite said third spring.

2. The invention of claim 1 wherein said upright segment is positioned on the side of said third spring re mote from said screen.

3. The invention of claim 2 wherein said upright segment is spaced from said spring a distance less than the elastic limit of said spring.

4. A parallax barrier for a color cathode ray tube comprising: a fragile, foraminous portion attached at its peripheral edge to walls of a rigid surrounding frame, said barrier being substantially rectangular in configuration and having a plurality of springs affixed to said walls, two of said springs being substantially oppositely disposed on the short sides of said frame and a third spring being attached on one of the long sides of said frame and extending therealong substantially parallel to the direction of said long side; and an upstanding member projecting perpendicularly from said frame side wall adjacent said third spring, said member having a flat side which is substantially parallel to saidspring.

5. The invention of claim 4 wherein said upstanding member is positioned on the side of said spring remote from said foraminous portion.

6. The invention of claim 5 wherein said upstanding member is formed as an L-shaped piece with one leg of the L affixed to said frame side wall. 

1. A substantially rectangular color cathode ray tube comprising: an evacuated envelope having at one end an enlarged face plate portion with a mosaic phosphor screen on the interior surface thereof and at the other end thereof an electron gun formed to provide electron beams directed to impinge upon said screen; and a parallax barrier to aid in color selection mounted adjacent said screen, said barrier comprising a relatively fragile foraminated portion attached at its peripheral edge to a circumferential frame, said barrier being supported bY means of three elongated support springs attached at one of their ends to a side wall of said frame and at the other of their ends to a side wall of said tube, two of said springs being attached to the short sides of said frame and the third spring being attached to one of the long sides; and extending therealong substantially parallel to the direction of said long side; said two of said springs being oppositely positioned to inherently define a pivot plane therebetween; and means formed adjacent said third spring and having a flat side substantially parallel thereto and attached to said frame and extending therefrom in a direction substantially normal to said frame for restricting the tendency of said barrier to pivot when said tube is dropped upon the edge opposite said third spring.
 2. The invention of claim 1 wherein said upright segment is positioned on the side of said third spring remote from said screen.
 3. The invention of claim 2 wherein said upright segment is spaced from said spring a distance less than the elastic limit of said spring.
 4. A parallax barrier for a color cathode ray tube comprising: a fragile, foraminous portion attached at its peripheral edge to walls of a rigid surrounding frame, said barrier being substantially rectangular in configuration and having a plurality of springs affixed to said walls, two of said springs being substantially oppositely disposed on the short sides of said frame and a third spring being attached on one of the long sides of said frame and extending therealong substantially parallel to the direction of said long side; and an upstanding member projecting perpendicularly from said frame side wall adjacent said third spring, said member having a flat side which is substantially parallel to said spring.
 5. The invention of claim 4 wherein said upstanding member is positioned on the side of said spring remote from said foraminous portion.
 6. The invention of claim 5 wherein said upstanding member is formed as an L-shaped piece with one leg of the L affixed to said frame side wall. 